And then he just sort of vanished!

He was barely seen again until Thursday, March 9, when he popped up in photos posted to Twitter. Several hours later, on Friday, he left London and returned to the Nigerian capital — nearly two months after leaving.

They also refused to disclose exactly what medical condition was keeping the 74-year-old in London or even prove he was, you know, alive.

The sketchiness from officials might have something to do with the fact that Nigerians aren't huge fans of Buhari's trips abroad.

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Last year, Buhari flew to London for 10 days allegedly for treatment for an ear infection — a move that sparked anger about the state of Nigeria's own health system. Diplomats have said Buhari has sometimes secretly routed trips as far as Asia via London so as not to have to declare medical leave all the time.

While he was nowhere to be seen, Nigerians had to make do with a bizarre series of second-hand stories about Buhari, like when they heard US President Donald Trump was set to hold a call with him — still in London.

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The official line was that the president is "hale and hearty," and just needed to get some "rest."

The whole thing also had people feeling a really intense sense of déjà vu.

Back in November 2009, then-president Umaru Yar'Adua also took what was supposed to be a quick medical leave to Saudi Arabia. Because it was supposed to be a short leave, he never officially handed power over to the vice president, which meant the country was on autopilot until he returned six long months later — only to die within three days.

Everyone was especially anxious this time, though, about The Case of the Missing President because Nigeria — Africa's largest economy — is currently suffering a recession for the first time in a quarter century.

Afolabi Sotunde / Reuters

A famine is brewing in the country's northeast. Sky-rocketing food prices have been squeezing families already hit by inflation.

Nigeria depends on oil for most of its government revenues, which means some of its economic woes were out of Buhari's hands due to plunging global oil prices. But disastrous economic policies haven't helped, including some that failed to work when Buhari first tried them as a military ruler more than two decades ago.

A few weeks after Buhari left, he finally handed over the reins to his vice president, Yemi Osinbajo. And things under the acting president have actually been going...better.

Osinbajo has also relaxed visa rules to lure foreign investors — a plan drawn up by Buhari but which, like many other plans, has been stuck in his chief of staff's office, according to diplomats.

Afolabi Sotunde / Reuters

Buhari is routinely criticized for his frequent trips abroad and tendency to speak with the foreign press. Osinbajo, however, has undertaken a flurry of visits to several states at home. That's included trips to Lagos, the commercial capital, and the oil-producing Niger Delta, where militants have sabotaged pipelines as the petrodollars have failed to trickle down. Buhari had failed to visit either location during almost two years at the helm.

Osinbajo has also been reaching out to ordinary Nigerians on a level unusual in the country.

He's met with state officials to discuss tackling soaring food prices. And during a trip to Lagos's international airport, he personally inspected broken facilities, including air conditioners, toilets, and luggage carousels. The following day, he fired the bosses of Nigeria's civil aviation, to the cheers of anyone who has travelled through Lagos airport.

All of this should have been good news, in many ways. But this is Nigeria. So despite Osinbajo making it clear he is loyal to his boss, there were leaked reports that Buhari’s inner circle were tracking the acting president's rising popularity with growing suspicion.

However, Buhari said on Friday he wants the veep to stay on as acting president while he continues to recuperate.

Buhari’s nickname among Nigerians is "Baba Go-Slow" and in 2015, when he took office, a hashtag called #BabaWhileYouWereGone started trending. It started trending again this month, but with a very different meaning.